- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Hot electron-induced electrochemiluminescence at cellulose derivatives-based composite electrodes
摘要： The possibility of using cellulose derivative films as (i) insulating material on metal electrodes or (ii) in composite electrode films on metal to produce hot electron-induced electrochemiluminescence (HECL) was studied. It was shown that the luminophores known to produce HECL at thin insulating film coated cathodes (e.g. Si/SiO2 and Al2O3 electrodes) produced HECL with the present novel electrodes. In the case of composite films consisting of cellulose material doped with conducting carbon particles, the optimal cellulose/carbon black ratios were investigated by measuring the time-resolved HECL (TR-HECL) of an aromatic Tb(III) chelate. In addition to Tb(III) chelate, other well-known labels, fluorescein and Ru(bpy)3 2+ chelate, were demonstrated to produce strong HECL at the present composite electrodes, which are more environmental friendly in disposable assay cartridges as the plastic-based composites we have studied previously. Thus, it is now possible on the present basis to manufacture biodegradable paper-based assay cartridges with HECL detection of labels at biodegradable electrodes. It was shown that the present composite films are stable over wide pH range, and also time-resolved detection of Ru(bpy)3 2+ chelate is possible although its luminescence lifetime if quite short. The calibration curves were measured for presently used aromatic Tb(III) chelate and for Ru(bpy)3 2+. The detection limit (s/n = 3) was 2 · 10?10 M for the Tb(III)-chelate and 4 · 10?9 M for Ru(bpy)3 2+ in time-resolved detection mode. The relative standard deviation for Tb(III)-L1 (n = 5) emission at 10?5 M concentration was 2%. Wide linear range and low detection limits suggests that cellulose based composite electrodes can be used in HECL bioaffinity assays which was finally demonstrated here by an immunometric immunoassay.
关键词： Bioaffinity assays,Cellulose derivatives,Lanthanide electrochemiluminescence,Immunoassays,Electrochemiluminescence,Hot electron electrochemistry
更新于2025-09-23 15:23:52
-
Recent advances of plasmonic nanoparticle-based optical analysis in homogeneous solution and at the single-nanoparticle level
摘要： Plasmonic nanoparticles with special localized surface plasmon resonance (LSPR) characters have been widely applied for optical sensing of various targets. With the combination of single nanoparticle imaging techniques, dynamic information of reactions and biological processes is obtained, facilitating the deep understanding of their principle and design of outstanding nanomaterials. In this review, we summarize the recently adopted optical analysis of diverse analytes based on plasmonic nanoparticles in both homogeneous solution and single-nanoparticle level. A brief introduction of LSPR is first discussed. Colorimetric and fluorimetric homogeneous detection examples by using different sensing mechanisms and strategies are provided. Single plasmonic nanoparticle-based analysis is concluded in two aspects: visualization of chemical reactions and understanding of biological processes. The basic sensing mechanisms and performances of these systems are introduced. Finally, this review highlights the challenges and future trend of plasmonic nanoparticle-based optical analysis system.
关键词： Plasmonic nanoparticles,Single-nanoparticle level,Fluorimetric assays,Chemical reactions,Localized surface plasmon resonance (LSPR),Optical analysis,Homogeneous solution,Colorimetric assays,Biological processes
更新于2025-09-23 15:21:01
-
A Biomimetic Plasmonic Nanoreactor for Reliable Metabolite Detection
摘要： Reliable monitoring of metabolites in biofluids is critical for diagnosis, treatment, and long-term management of various diseases. Although widely used, existing enzymatic metabolite assays face challenges in clinical practice primarily due to the susceptibility of enzyme activity to external conditions and the low sensitivity of sensing strategies. Inspired by the micro/nanoscale confined catalytic environment in living cells, the coencapsulation of oxidoreductase and metal nanoparticles within the nanopores of macroporous silica foams to fabricate all-in-one bio-nanoreactors is reported herein for use in surface-enhanced Raman scattering (SERS)-based metabolic assays. The enhancement of catalytical activity and stability of enzyme against high temperatures, long-time storage or proteolytic agents are demonstrated. The nanoreactors recognize and catalyze oxidation of the metabolite, and provide ratiometric SERS response in the presence of the enzymatic by-product H2O2, enabling sensitive metabolite quantification in a “sample in and answer out” manner. The nanoreactor makes any oxidoreductase-responsible metabolite a candidate for quantitative SERS sensing, as shown for glucose and lactate. Glucose levels of patients with bacterial infection are accurately analyzed with only 20 μL of cerebrospinal fluids, indicating the potential application of the nanoreactor in vitro clinical testing.
关键词： metabolic assays,metabolic testing,macroporous silica foams,biomimetic nanoreactors,SERS biosensors,enzymes
更新于2025-09-23 15:19:57
-
Rapid and Straightforward Quantification of Recombinant Proteins Using Fluorescence Polarization
摘要： Biotechnology enables the production and commercialization of recombinant proteins for diagnostic, therapeutic and research applications. For instance, monoclonal antibodies nowadays represent a fast growing market that accounts for almost half of the biopharmaceutical compounds business with $75 billion turnover in 2013. Quantification of proteins is an important task in order to optimize cell culture conditions and ensure that every step of the production process is in line with the specifications. For therapeutics, precise and reliable dosage is mandatory to avoid adverse effects for the patients. Current analytical techniques such as ELISA or HPLC are time-consuming and often require purification prior to analysis. In this context, there is a strong demand for a technology that would be to protein quantification what a balance is to weight measurement: rapid, precise, accurate, robust, and straightforward. To this effect, we have developed an assay for the rapid quantification of recombinant proteins. It is based on fluorescence polarization and requires little or no pretreatment of samples. Fluorescence anisotropy of a small specific fluorescent ligand increased upon binding to its recombinant target protein, e.g. a monoclonal antibody, enabling quantification. The assay did not require prior separation of biotechnological cultures making it as straightforward as weighing using a balance. Monitoring of the production of a representative His-tagged protein during E.coli fermentation was obtained by regular sampling and assaying using the fluorescence polarization assay.
关键词： Fluorescence,Recombinant proteins,Assays,Biotechnology,Antibodies
更新于2025-09-19 17:15:36
-
Simple geometrical modifications for substantial color intensity and detection limit enhancements in lateral-flow immunochromatographic assays
摘要： One of the ongoing challenges in lateral flow Immunochromatographic assays (LFIA), is lowering the limit of detection and enhancing their signal quality, i.e. the color intensity. There are a number of rather costly and complicated processes for this aim, such as the use of functionalized materials/membranes and additional spectroscopic readout units. Nonetheless, there are simple and easy to practice alternatives, to be uncovered by analyzing the essential parameters of immunological reactions. The color intensity of the test line is a function of analytes flow velocity and their reaction rate. Detection pad width and test line position impact the flow velocity and reaction rate kinetics, examined in this paper for the limit of detection (LOD) and test-line color intensity. Firstly, the impact of width on the LOD was examined for human chorionic gonadotropin (pregnancy biomarker). Test line color intensity was measured using five different widths of the detection pad (trapezoidal) and four different test line positions, and the trends observed were explained according to the measured evolution of the velocity along the chromatography paper. With a constant width absorbent pad, LOD was cut by half to 5 mIU/ml by using a narrowing width detection pad, which keeps the wicking velocity higher than normal strips, and compared to them, color intensity increase between 55-150%, depending on the concentration. Nevertheless, a widening detection pad might cut the color intensity up to 150%, compared to normal strips, due to a profound decline of the analyte to ligand ratio at the test line. In addition, adequately sending the test line away from the conjugate pad yields the highest possible color intensity, for up to 400% of increase, in lower concentrations and narrowing test pads. However, further distancing the test line downfalls the color intensity.
关键词： Lateral Flow Immunochromatographic Assays,Trapezoidal Geometry,Limit of Detection,Detection Pad,Capillary Flow Velocity,Porous Medium,Color Intensity,Test Line Displacement
更新于2025-09-19 17:15:36
-
Preparation of Highly Stable and Photoluminescent Cadmiuma??Free InP/GaP/ZnS Core/Shell Quantum Dots and Application to Quantitative Immunoassay
摘要： Indium phosphide (InP) quantum dots (QDs) are ideal substitutes for widely used cadmium-based QDs and have great application prospects in biological fields due to their environmentally benign properties and human safety. However, the synthesis of InP core/shell QDs with biocompatibility, high quantum yield (QY), uniform particle size, and high stability is still a challenging subject. Herein, high quality (QY up to 72%) thick shell InP/GaP/ZnS core/shell QDs (12.8 ± 1.4 nm) are synthesized using multiple injections of shell precursor and extension of shell growth time, with GaP serving as the intermediate layer and 1-octanethiol acting as the new S source. The thick shell InP/GaP/ZnS core/shell QDs still keep high QY and photostability after transfer into water. InP/GaP/ZnS core/shell QDs as fluorescence labels to establish QD-based fluorescence-linked immunosorbent assay (QD-FLISA) for quantitative detection of C-reactive protein (CRP), and a calibration curve is established between fluorescence intensity and CRP concentrations (range: 1–800 ng mL?1, correlation coefficient: R2 = 0.9992). The limit of detection is 2.9 ng mL?1, which increases twofold compared to previously reported cadmium-free QD-based immunoassays. Thus, InP/GaP/ZnS core/shell QDs as a great promise fluorescence labeling material, provide a new route for cadmium-free sensitive and specific immunoassays in biomedical fields.
关键词： cadmium-free,quantum dot-based fluorescence-linked immunosorbent assays,thick shell InP core/shell quantum dots,C-reactive proteins,quantitative detection
更新于2025-09-19 17:13:59
-
Portable Multiplex Optical Assays
摘要： Global health issues are increasingly becoming critical with high fatality rate due to chronic and infectious diseases. Emerging technologies aim to address these problems by understanding the causes of lethal conditions and diagnosing symptoms at early stage. Existing commercial diagnostics primarily focus on single-plex assays due to ease-of-use, simplicity in analysis, and amenability to mass manufacturing. Many research grade devices have utilized only a few molecular and morphological signatures in bodily fluids. However, multiplex devices can improve accuracy, sensitivity, and scalability of research and diagnostic devices. This review presents multiplex assays that utilize optical, electrical, and chemical methods and materials that have the potential to improve portable point-of-care diagnostics. The critical role of emerging optical and complementary assays with multiple contrast mechanisms is investigated to enable highly multiplex analysis in field settings. Multiparameter portable devices for field applications toward health monitoring, food testing, air quality monitoring, and microanalysis in other extreme conditions are examined. Current trends indicate the need for validation of health diagnosis based on a large number of biomarkers in randomized clinical trials. Advanced digital analysis, crowd-sourced solutions, and robust user interfaces will become an integral part of the connected global health systems and personalized monitoring platforms.
关键词： optical assays,digital analysis,diagnostic devices,point-of-care,multiplex devices,portable devices,mobile health
更新于2025-09-10 09:29:36
-
Molecularly Imprinted Fluorescent Test Strip for Direct, Rapid, and Visual Dopamine Detection in Tiny Amount of Biofluid
摘要： Paper-based assays for detection of physiologically important species are needed in medical theranostics owning to their superiorities in point of care testing, daily monitoring, and even visual readout by using chromogenic materials. In this work, a facile test strip is developed for visual detection of a neurotransmitter dopamine (DA) based on dual-emission fluorescent molecularly imprinted polymer nanoparticles (DE-MIPs). The DE-MIPs, featured with tailor-made DA affinity and good anti-interference, exhibit DA concentration-dependent fluorescent colors, due to the variable ratios of dual-emission fluorescence caused by DA binding and quenching. By facile coating DE-MIPs on a filter paper, the DA test strips are obtained. The resultant test strip, like the simplicity of a pH test paper, shows the potential for directly visual detection of DA levels just by dripping a tiny amount of biofluid sample on it. The test result of real serum samples demonstrates that the DA strip enables to visually and semiquantitatively detect DA within 3 min by using only 10 μL of serum samples and with a low detection limit ((100–150) × 10?9 m) by naked eye. This work thus offers a facile and efficient strategy for rapid, visual, and on-site detection of biofluids in clinic.
关键词： molecular imprinting,dual-emission fluorescence,visual detection,paper-based assays,dopamine
更新于2025-09-10 09:29:36
-
Micromachined optical flow cell for sensitive measurement of droplets in tubing
摘要： Here a micromachined flow cell with enhanced optical sensitivity is presented that allows high-throughput analysis of microdroplets. As a droplet flows through multiple concatenated measurement points, the rate of enzymatic reaction in the droplet can be fully characterized without stopping the flow. Since there is no cross-talk between the droplets, the flow cell is capable of continuously measuring biochemical assays in a droplet flow and thus is suitable to be used for continuous point-of-care diagnostics monitoring. This paper describes the design and operation of the device and its validation by application to the accurate and continuous quantification of glucose concentrations using an oxidase enzymatic assay. The flow cell forms an important component in the miniaturization of chemical and bio analyzers into portable or wearable devices.
关键词： Enzymatic assays,Droplet microfluidics,Optical detections,Microfluidics,Real-time monitoring,Continuous measurement,Absorbance,Point-of-care diagnostics
更新于2025-09-10 09:29:36
-
Recent Advances in Design of Fluorescence-based Assays for High-throughput Screening
摘要： Significant improvements in disease management have been achieved in the past few decades. Using cancer as an example, survival rates have increased dramatically in economically developed countries, according to the World Cancer Report published by WHO in 2014.1 One of the highlights is the average 5-year survival rate of children diagnosed before the age of 15 years in Britain increased from less than 30% in 1966-70 to almost 80% in 1996-2000. The improvement can be attributed to the establishment of early screening and awareness programs, identification of a large number of genetic or non-genetic risk factors or markers, and availability of diverse therapeutic strategies including surgery and treatments using radioactive reagents, small molecules, or biological drugs. Still, cancer remains one of the major causes of deaths worldwide, affecting millions of people. Survival rates in developing countries are poor, and the global and regional burden of cancer in terms of both incidence and mortality keep increasing along with the growing population and aging society. Further improvement heavily relies on early diagnosis, wide access to treatment options, and discovery of more effective biomarkers as well as anticancer drugs with high efficacy. Such demands are also applied to diagnosis and cure for all other diseases, calling for rapid advancements in high-throughput screening (HTS) technologies that can efficiently test a large number of targets and samples, monitor diverse enzymatic processes in situ, and effectively identify biologically active substances.2
关键词： Fluorescence-based assays,High-throughput screening,Disease diagnosis,Drug discovery,Biomarkers
更新于2025-09-09 09:28:46